Do you have anything that can control Poa Annua in St. Augustine grass?
What about getting rid of Bermuda grass in St. Augustine?
ATRAZINE will handle the Poa Annua. You can read details on it’s label. However, Bermuda and St. Augustine are closely related and any product currently on the market that will kill Bermuda will most likely kill the St. Augustine as well. The most common Bermuda killer we sell is the TURFLON. It’s fine for fescue and bluegrass blends but will injure the St. Augustine if you broadcast it over the entire yard.
So your choices are to hand remove the Bermuda or try to isolate your treatments to just those patches. I have seen where people will use a weak mixture of Turflon and apply it to the center patches of Bermuda and carefully avoid getting any on the St. Augustine. This is not the most effective approach but it will save some time. And over the course of a few treatments, you can kill off 90+% of the Bermuda without hurting the St. Augustine so it’s somewhat effective.
Here are direct links to the information and products listed above: